(1) Field of the Invention
The present invention relates to an acrylic laminated diffuser panel comprising an integrated laminate including at least an acrylic resin film having a high-light-diffusing property and an acrylic resin plate and a process for the preparation of this acrylic laminated diffuser panel.
More particularly, the present invention relates to an acrylic laminated light diffuser panel comprising a laminate in which an acrylic resin film having a light-diffusing agent-containing layer formed thereon or an acrylic resin film containing a light-diffusing agent therein is laminated on an acrylic resin plate preferentially on one surface thereof, wherein said acrylic resin film is integrated with said acrylic resin plate by polymerization of a starting monomer of said acrylic resin plate or its partially polymerized product in the state where said acrylic resin film is partially dissolved and/or swollen by said monomer or said partially polymerized product or an acrylic polymerizable binder. The present invention also relates to a process for the preparation of this acrylic laminated light diffuser panel.
(2) Description of the Prior Art
An acrylic resin plate having, coated thereon, a layer containing an appropriate light-diffusing agent has heretofore been used as a rear projection screen, for example, in the field of a day-light screen (a screen on which a projected image can be viewed even in a bright place).
Recently, a rear projection screen is ordinarily prepared by coating a composition comprising a light-diffusing agent such as glass powder, titanium oxide, silicon oxide or calcium carbonate, a coloring agent, a binder and a diluent on one surface of a commercially available acrylic resin plate, styrene type resin plate or polycarbonate plate by spray coating, rotary coating, roll coating or flow coating, and drying and solidifying the coated composition, as disclosed in Japanese Patent Publications No. 20,857/77 and 8,248/73.
As the characteristic properties that such rear projection screens should possess, there can be mentioned total luminous transmittance, gain, reflectance, haze, diffusion rate, bending angle, contrast and resolving power. When a certain light-diffusing agent is used, these characteristics are influenced by the thickness uniformity of the light-diffusing layer, though the degree differs to some extent among these characteristics. Accordingly, in the conventional processes for the production of rear projection screens, great efforts and attention have been paid to uniformalization of the thickness of the light-diffusing layer, with the result that the coating operation becomes complicated and troublesome and requires a high degree of skill and much labor. Furthermore, the size of a substrate that can be coated, for example, an acrylic resin plate, is limited. Moreover, at the step of drying and curing a coated layer containing a light-diffusing layer, the treatment should be carried out very carefully for each plate, and also this treatment requires a large place and much labor. Furthermore, since the light-diffusing agent-containing layer is exposed to the outside, care should be taken to remove dust and to prevent the of adhesion of dust. As means for obviating these disadvantages, there is known a method in which two transparent plastic sheets are applied to both the surfaces of the light-diffusing agent-containing layer, respectively, as proposed in Japanese Utility Model Publications No. 537/65 and 21,110/69. However, in this method, it is very difficult to apply such transparent plastic sheets without incurring optical defects, and the strength of the resulting laminated structure is insufficient.